This invention relates to a shock absorber, and more particularly, the invention relates to a shock absorber having a fluid passageway in the piston rod for damping adjustment.
Shock absorbers are used in vehicles to dampen inputs from roadways. For some vehicle applications, such as snowmobiles, it may be highly desirable to provide the operator the ability to externally adjust damping characteristics of the shock absorber. To this end, some shock absorbers have incorporated a fluid passageway in the shock absorber piston rod to fluidly connect the rebound and compression fluid chambers. The rod has included a longitudinal bore with a plunger arranged within the bore. An adjustment knob, which is accessible to the vehicle operator from the exterior of the shock absorber, cooperates with the plunger to move the plunger between various positions to control the flow of fluid through the passageway. In this manner, damping characteristics may be adjusted by the operator.
Adjusting the plunger in the manner described above has affected the damping characteristics for both the rebound and compression strokes of the shock absorber. However, for a particular application it may be desirable to provide adjustment of the plunger that affects the damping characteristics for only one of the compression or rebound strokes. Therefore, what is needed is through the rod damping adjustment that affects the damping characteristics for one of the rebound or compression strokes.
The present invention provides a shock absorber including a shock absorber body defining a cavity that is at least partially filled with hydraulic fluid. A piston is slidably arranged within the body and separates the cavity into rebound and compression fluid chambers. A rod is secured to the piston and includes first and second portions that are respectively adjacent to the rebound and compression chambers. A fluid passageway extends between the first and second portions to fluidly connect the rebound and compression chambers. In this manner, fluid is permitted to flow through the rod to provide damping characteristics in addition to those damping characteristics typically provided by the piston. A valve assembly, which may include a one-way check valve, is arranged within the passageway for controlling the flow of fluid between the rebound and compression chambers through the passageway. Preferably, the rod includes a longitudinal bore having an adjustable plunger arranged therein. The plunger may be adjusted by a knob to move the plunger to block at least a portion of the passageway to further control the flow of hydraulic fluid through the passageway.
Accordingly, the above invention provides through the rod damping adjustment that affects the damping characteristics for one of the rebound or compression strokes.